Well tool having safety means to prevent premature firing



Jan. 30, T958 1 3` KmLEY ET AL WELL TOOL HAVING SAFETY MEANS TO PREVENT PREMATURE FIRING 3 Sheets-Sheet l l VENTORS TTORVE YS Jan. 30, 1968 J. c. KaNLEY ET AL B@ WELL TOOL HAVING SAFETY MEANS TO PREVENT PREMATURE FIRING Filed Aug. 18, 196:',

5 Sheets-Sheet 2 am 39, T1968 1. c. KINLEY r-:TAL 3,3%,379

WELL TGOL HAVING SAFETY MEANS TO PREVENT PREMATURE FIRING Filed Aug. le, 1965 3 Sheets-Shea. 5

TTRNEYS United States Patent O ...i Winn-wr..

ABSTRACT 0F THE DiCLUSlURE A well tool, such as a perforator, which is actuated by detonating an explosive charge, having a safety means to prevent premature firing of the explosive.

In United States Patent No. 2,554,601, a tubing perforator of the general type for inserting an orifice insert or flow control device in a tubing or pipe with an explosive is disclosed.

Summary of the invention The field of this invention is explosive-actuatzd Well tools such as perforators for inserting an orifice insert or fiow control device in a well pipe. The present invention has a safety means which prevents premature firing of the explosive and which is actuated by moving the tool longitudinally upwardly in the well.

An object of this invention is to provide a new and iniproved well tool and particularly a new and improved safety means which is suitable for use with the perforator disclosed in said Patent No. 2,554,60l as Well as other well tools.

An important object of this invention is to provide a new and improved safety means which prevents premature ring of an explosive-actuated tool.

Another object of this invention is to provide a new and improved safety means for use in an explosive-actuated tool so that downward jarring action may be utilized without tiring the explosive until the safety means is released, whereby the tool may be moved downwardly in a well pipe past obstructions such as caused by crooked tubing, deposits of scale, a pipe nipple and the like.

Yet another object of this invention is to provide a new and improved safety means wherein a cylindrical housing having a means therein coacting with a rod positioned longitudinally in the housing is provided to prevent movement of the rod relative to the housing until a releasable latch means in the housing is released to allow movement of the rod relative to the housing.

A particular object of this invention is to provide a new and improved safety means wherein a safety body means having a firing pin rod longitudinally therein is provided with a safety pin means coacting with the firing pin rod to prevent downward movement of the firing pin rod to contact a firing pin and a safety block means attached to the safety pin means for rotating the safety pin means to diminish coaction between the firing pin body and the safety pin means which thereby permits the firing pin rod to move in a downward direction until it contacts the firing pin.

Still another object of the present invention is to provide a new and improved safety means wherein a safety tripper is provided to release a safety block means and thereby permit rotation of a safety pin means wherein the rotation releases a ring pin rod for movement.

A further object of this invention is to provide a new and improved safety means wherein a safety body having a firing pin rod longitudinally disposed therein is provided with a safety spring means connected to the safety body 3,3%79? Patented Jian. 30, 1968 and connected to a safety block, which upon releasing or diminishing tension in the spring by the tripping of a safety tripper, rotates the safety block which in turn rotates a safety pin in coacting engagement with the firing pin rod to permit the firing pin body to move downwardly to contact the firing pin.

The preferred embodiment of this invention will be described hereinafter together with other features thereof, and additional objects will become evident from such description.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof wherein an example of the invention is shown and wherein:

FIG. l is an elevation, partly in section, illustrating the tubing perforator and the safety means therewith before the perforator has been fired for inserting an orifice insert or other flow control device into a tubing or well pipe;

FIG. 2 is an elevation, with certain portions dotted, illustrating the tubing perforator in a seated position and ready to tire an orifice insert or the like into the well pipe or tubing;

FIG. 3 is a view similar to FIG. 2, but illustrating the tubing perforator after it has been fired to insert the orifice into tubing or well pipe;

FG. 4 is an elevation, partly in section, of the safety means in the running-in position;

FIG. 5 is a sectional view taken along lines 5-5 of FIG. 4 showing further details of the safety means of this invention;

FIG. 6 is a cross-sectional view taken along lines 6 6 in FIG. 4;

FIG. 7 is a sectional view of the safety means, partly in elevation, illustrating the safety means in its released position;

FiG. 8 is a cross-sectional view taken along lines 8-8 of FIG. 7; and

FIG. 9 is an isometric view of a portion of the safety means of this invention removed from the rest of the structure for illustration purposes.

In the drawings, the letter A designates generally a tubing perforator of a type which inserts an orifice insert or other flow control device C into a well pipe or tubing D for the purpose of controlling fluid flow into the tubing or pipe D from a well formation. The perforator A is adapt-rd to be located prior to firing at a tubing collar or pipe joint F in the pipe string D. The perforator A is fired by the manipulation of a wireline W on which the perforator tool A is lowered into a well pipe D, or a suitable weight L may be dropped along the wireline for detonating the explosive charge in the explosive means G of the A, as will be explained. Such explosion effects the insertion of the Orifice insert C to the position shown in FIG. 3 and thereafter the tool A is removed from the particular location in the tubing B leaving the insert C in position within the tubing or pipe D for ow control therethrough. The present invention includes a safety means B which is incorporated into the perforator A for preventing a premature firing of the exposive in the explosive means G. This is especially of value when downward jarring is required on the perforator A to force the perforator A through obstructions in the pipe D such as caused by crooked tubing, deposits of scale, a pipe nipple and the like.

In the particular embodiment illustrated in the drawings, the perforator A includes a firing pin body 1t) which is positioned within a sleeve 11 by means of suitable shear pins (not shown) but which t into the arcuate recesses 12 shown in FIG. 4. With the use of such shear pins, the sleeve 11 may be separated from the firing pin body 10 by a manipulation of the wireline W supporting the tool A, if such becomes desirable or necessary, so that the fishing neck 16a at the upper end of the body 1d is exposed for fishing operations, as will be understood by those skilled in the art.

The upper bore b of the firing pin body has a firing pin rod 14 therein which extends through the safety means B and is adapted to move downwardly and impart movement to a tapered firing pin 15 which is located in tapered lower bore 10c of the firing pin body 1i). rThe lower external end of the body 1tl is provided with external buttress threads 10d.

The sleeve 11 has one or more openings 11a to prevent a fluid lock in the housing or sleeve 11 as a punch 16 moves with respect to such sleeve 11. The punch 16 is provided with an upper inclined annular shoulder 16a which engages a corresponding internal shoulder 11b in the sleeve 11 so that when the punch 16 is in the raised position, the entire tool A is supported from the wireline W or other means extending to the surface of the well.

In the preferred form of the invention, the punch 16 is suspended in an upper position by means of a shear pin 19 or other suitable means which is adapted to be sheared upon a downward movement of the punch 16. Upon the downward movement of the punch 16, the lower reduced diameter portion 161) of the punch 16 enters the bore 10b of the tiring pin body 10 to strike the upper end of the firing pin rod 14. The upper end of the punch 16 may be connected to the wireline W in any suitable manner, but as shown in FIGS. 1-3, an adapter 20 is connected by threads 16C or other suitable connecting means to the adapter 20. Wireline jars of known construction are usually connected above the adapter 20.

As shown in FIGS. l-3, the intermediate portion 110 of the firing pin body 10 serves as the safety body or housing and has an enlarged external diameter so as to provide a shoulder 111m which is engaged Iby the lower end of the sleeve 11. The bore 10b extends through the intermediate safety body or housing 110` so that the firing pin rod 14 is movable therein as will lbe more evident hereafter. The safety body 110 is provided with oppositely disposed longitudinally extending slots or openings 110b and 110C which extend to the bore 10b for a purpose to be hereinafter explained.

The firing pin rod 14, as seen in FIGS. 4, 5 and 7, is provided with a fiat recess 14a which slopes upwardly at each end until merging with the circular surface of rod 14. An arcuate recess 14b is provided in the rod 14, preferably adjacent one of the fiat recesses 14a. The safety means B includes a rotatable pin or latch pin 21 which extends into a hole 110C! transversely to, and preferably substantially perpendicular to, the tiring pin rod 14 as seen in FIGS. 4, 5 and 7. The rotatable lpin 21 as seen in FIGS. 6, 8 and 9 is provided with a semicircular or arcuate recess 21a; adjacent the semicircular recess 21a is a grooved recess 2111 which receives an end 23a of a safety block 23 which is welded integrally or otherwise suitably secured to the latch pin 21 for rotation therewith. The rotatable pin 21 also has a recess 21C for receiving the upper end of a safety spring 26 which extends through an opening 23h in the block 23. The lower end of the spring 26 is connected to a fastening pin 28 or other suitable means so as to hold the spring 26 under tension for a purpose to be hereinafter explained.

As seen in FIGS. 4-6, the pin 21 has a cylindrical surface 21d which ts into the arcuate recess 14h of firing pin rod 14 to prevent downward movement of the rod 14 and in this position semicircular recess 21a is on the opposite side of the coacting cylindrical surface 21d and the inner surface of the recess 1411 (FIG. 6). The end 23a of the block 23 is urged downwardly as the pin 21 and the block 23 are rotated together by the safety spring means 26. During the running in of the tool A, the end 23a of the `block 23 is prevented from such downward movement at the urging of the safety spring means 26 by the engagement of the end 231') with safety tripper 3l? which is disposed in the slot 11012 on a pivot pin 31. rlfhe pivot pin 31 extends transversely to Bring pin rod 14 through an opening in the body 110, and is provided with an enlarged pivot pin head 31a as seen in FIGS. 4 and 5. rl`he safety tripper 311 is provided with an opening 3d!) which is wider adjacent a shear pin 32 to permit the tripper 311 to move laterally during the running in of the tool with respect to the pivot pin head 31a.

During the running in of the tool A, the safety block 23 is held in the position as shown in FIG. 4 by the tripper 3G, since the tripper 30 is held in an upwardly exten-ding position during the running in of the tool A by the shear pin 32. The shear pin 32 is positioned in the housing 116 transverse to tiring pin rod 14 and is adapted to be sheared by the engagement of the upper edge 39a of the tripper 3i) with the inside of a collar or joint F (FIG. l). Such releasing or tripping of the releasable latch means or tripper 3@ shears the pin 32 and allows the tripper 3@ to partially rotate around pivot pin 31 and to swing or drop below the safety block 23 (FIG. 7) whereby the end 23a of the safety block 23 is moved downwardly by the action of the safety spring means 26. The yblock 23 rotates in a counterclockwise direction as viewed in FIGS. 4 and 7 until the end strikes a stop pin 34 which is positioned in the housing 110 through a hole 34a and transversely to the iirin g pin rod 14. The rotation of the safety block 23 is imparted to the safety pin 21 so that it also rotates in a counterclockwise direction until the wall of the recess 21a of the pin 21 is parallel to and alongside the external cylindrical surface 14C of the ring pin rod 14 (FIGS. 7 and 8).

When the coaction between the surface 21d of the pin 21 and the surface 14h of the firing pin rod 14 is released, the ring pin rod 14 may move in a downward direction to contact the ring pin 15. It should be noted that if such downward movement occurs, it does not strike the firing pin 15- with sufficient force to discharge the explosive means G.

The explosive means G includes an explosive chamber body 25 which is connected to the body 10 by any suitable connecting means such as threads 10d (FIG. 4) which engage with corresponding threads in the chamber body 25. An explosive housing or cartridge 33 for explosive 34 is positioned within the body 25 with a seal 35 therebelow. For detonating such explosive charge 34, a detonator 38 such as a shot gun shell or a blank cartridge is provided and is mounted above the powder 34. The lower end of the tiring pin 15 is adapted to strike the detonator 33 for the detonation thereof and the subsequent explosion of the explosive powder or charge 34.

A driving wedge 4d having an inclined surface 40a which is behind and in engagement with an inclined surface 41a of a carrier 41 is disposed in a barrel 39. The carrier 41 is adapted to slide laterally in a suitable slot or groove 39a in the barrel 39. Normally, the carrier 41 is retained in its retracted position, shown in FIG. l, yby a shear pin (not shown) or other suitable means. The carrier 41 is releasably attached to the insert or other ow control device, as is well known, so that the insert C is released from the carrier 41 upon longitudinal movement of the tool A after the insert C is punched into the tubing D (FIG. 3).

In order to position the tool A at a desired elevation in the well pipe D, any conventional means may be used such as that illustrated wherein a spring loaded latch 45 is mounted on a pivot pin 46 near the lower end of the tool A. The latch 45 is urged laterally outwardly by a spring 47 or other resilient means so as to extend beyond the body 43 (FIG. 2). During the running in of the tool A, the latch 45 is held in a retracted position by a tripper 4S which is pivotally mounted on a pin 49. Such tripper 48 is held in an upwardly extending position during the running in of the tool A by a shear pin SSB which is adapted to be sheared by the engagement of the upper edge 48a of the tripper with the inside of collar F. Such tripping of the tripper 48 shears the pin 50 and allows it to swing or drop below the latch 45 whereby the latch 45 is moved by the resilent leaf spring 47 to its extended latching position (FIG. 2) for seating in the collar F. Thus, the tool A is located within a particular collar F so as to properly position the tool A prior to the firing of the explosive charge 34.

As explained in the above-mentioned Patent No. 2,554,601, the downward movement of .the wedge 40 is stopped by a stop wedge 60 having an inclined surface 69a and disposed at the lower end of the barrel 39. The stop wedge 60 has a iiuid passage 60C near its lower end which is in communication with a central opening 39a in the barrel 39. When the drive wedge 40 moves downwardly after having forced the carrier 41 and .the orifice insert C outwardly, it reaches a position where grease or other fluid contined below the wedge 40 is then compressed and is forced down through the opening 60C and into the opening 39a. The opening 39a is above a latch release piston 70 which is held in an upper retracted position by one or more shear pins (not shown) until compressed grease or fluid in the opening 39a acts on the piston '7d to shear the pins at which time a spring 69 acts to continue the downward movement of the piston 70 to cause the lower end thereof to push on an inclined surface 45a of the latch 45 which in turn causes a clockwise pivoting (FIG. 2) for retracting the latch 45 from the collar F.

In the operation or use of the tool A of this invention with its safety means B, the tool A is preferably lowered on the wireline W or other suitable support. While the tool A is being lowered in the tubing or pipe, the releasable latch means or safety tripper 30 and the tripper 48 are in the retracted positions shown in FIG. l and are held in such positions by shear pins 32 and 50, respectively. The safety tripper 3) thus serves to hold the safety block 23 in a retracted position as the tool A is lowered and the tripper 4S holds the latch 45 in its retracted position. As seen in FIG. 1, the punch 16 is in a raised position and is therefore spaced from the tiring pin rod 14. However, in the running in of the tool A, obstructions in the tubing or well pipe, such as mentioned above, may necessitate a downward jarring of the tool which might cause punch 16 to strike firing pin rod 14 with a sufficient force to detonate the explosive 34. With the safety means B in the tool, the punch 16 is prevented from striking firing pin rod 14 before the safety tripper or releasable latch means 3@ has been released, and thereby an accidental or inadvertent firing of the explosive 34 is prevented.

The tool A is lowered into the section of the pipe D below the joint or collar F on which the latch 45 is -to be seated. This positions the safety tripper 30 below the collar or joint F. Then the tool A is raised upwardly to engage the edge 30a of safety ltripper 3d in the collar or joint F to shear the pin 32. Upon the shearing of the pin 32, the safety tripper 30 drops to the position shown in FiGS. 2, 3, and 7, and the safety spring 26 causes rotation of the safety block 23 in a counterclockwise direction (as viewed in FIG. 4) which therefore causes the safety pin 21 to also rotate in a counterclockwise direction until the end 2311 of the safety block 23 contacts the stop pin 34. The coacting cylindrical surface 21d of the pin 21 and the surface 14e of the rod 14 are thus disengaged as previously explained so that the rod 14 is permitted to move downwardly relative to the housing 11h.

Upon a continued upward movement of the tool A, a shearing of the pin 50 is effected, so that the tripper 48 drops to the position shown in FIG. 2 and the spring 47 urges the latch 45 outwardly to its extended position. With the latch 45 in the extended position, the tool A is again lowered until such latch 45 catches in the tubing 6 or collar F to stop the downward movement of the tool A.

Thereafter, a weight L is dropped along the wireline W (FIG. 3), or the line W supporting the tool A is jerked or manipulated, preferably with a conventional wireline jarring tool or weight (not shown), to impart a downward force to the punch 16 which causes an impact blow by the punch 16 on the top of the firing pin rod 14. Such blow is transmitted from the rod 14 zto the ring pin 15 and to the detonator or shell 48. Upon the explosion of the detonator 38, the entire explosive charge 34 is detonated or fired. The explosion resulting from the firing of the explosive powder or charge 34 transmits a downward movement to the wedge 4t) which causes a coaction between its inclined surface 40a and the inner inclined surface 41a of the carrier 41 to move such carrier 41 laterally outwardly. The carrier 41 carries the insert C or other flow control device with its lateral movement to cause the orifice insert C to puncture through the pipe or tubing D.

The downward movement of the drive wedge 4t) continues until it is stopped by the stop wedge 60. Also, as explained above, when the drive wedge 4() reaches its lower limit, it forces the grease or other fluid under compression through the opening 39a above the piston '70 to effect a release of the latch 45 from the collar F so that the operator at the surface is thus signalled that the tool has been fired. With the orifice insert C in the tubing D as shown in FIG. 3, a longitudinal movement of the carrier 41 with the tool A severs the carrier 41 from the insert C and leaves the insert C or other flow control device in the pipe D after the tool A is moved.

Although the safety means B is disclosed with the perforator A, it should be noted that the safety means B can be used with other tools wherein a safety or latching function is desirable.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape, and materials: as well as in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. In a tool having a firing pin for firing a charge the improvement residing in a safety means for preventing accidental tiring of said charge, comprising:

(a) a safety body having a longitudinal bore therein,

(b) a tiring pin rod longitudinally aligned with said tiring pin and disposed in said longitudinal bore for longitudinal movement relative to said safety body,

(c) latch pin means mounted on said body and coacting with said firing pin rod for restraining said rod lfrom movement longitudinally into contact with said tiring pin,

(d) safety block means positioned within said body and extending from said latch pin means,

(e) a spring mounted with said body and operably connected to said block means `for imparting movement to said block means for the release of said latch pin means from latching engagement with said tiring pin rod,

(f) safety tripper means mounted on said body and extending therefrom and engaging said block means for preventing movement of said block means when said latch pin means is coacting with said firing pin rod to restrain the longitudinal movement thereof, and

(g) said tripper means being releasable from said block means for enabling said spring to .move said block means and said latch pin means rfrom coacting engagement with said firing pin rod to allow said iiring pin rod to move longitudinally for contact with said tiring pin.

2. The structure as claimed in claim 1 wherein said safety means includes:

(a) a stop pin mounted on said safety body and adjacent said firing pin rod to stop movement of said block means after being released by said tripper means.

3. In a tool having a firing -pin for firing a charge in pipe, the improvement residing in safety means for preventing unintentional iiring of said charge comprising:

(a) a housing having a longitudinal bore therein,

(b) a firing pin rod in said bore extending through said housing,

(c) means in said housing engaging said firing rod in a first position whereby said firing pin rod is restrained frorn contacting said firing pin,

(d) a springY operably connectedV to said engaging means and mounted with said body for moving said engaging Imeans to a second position, releasing said firing rod for contact With said pin,

(e) a releasable tripper extending from said housing and engaging said means to retain said engaging means in said first position, and

(f) said releasable tripper having a collar engaging means engageable with a collar of said pipe upon upward movement of said tool for moving said tripper to a position to permit said engaging means to move from said first to said second position to thereby permit said firing pin body to contact said ring pin.

4. The structure as claimed in claim 3 wherein said means in said housing engaging said firing pin rod comprises:

(a) a latch pin extending transversely into said hous ing for releasable latching engagement with said firing -pin rod, and

(b) a safety block connected to said latch pin engaging said releasable tripper and operably connected to said spring.

5. The structure as claimed in claim 3 wherein said safety means includes:

(a) a stop pin positioned in said housing adjacent said engaging means for positioning said means in said second position.

6. For use in a pipe having a collar, a tool having a firing pin for firing a charge in said pipe, the improvement residing in a safety means to prevent accidental firing of said charge comprising:

(a) a cylindrical safety body having a bore therein,

(b) a firing pin rod extending longitudinally through said bore of said safety body longitudinally aligned above said firing pin,

(c) a rotatable pin extending into said safety body transverse and substantially perpendicularly to said firing pin rod,

(d) said rotatable pin coacting with said firing pin rod to position said firing pin rod in a first position which restrains said firing pin body from downward movement to contact said firing pin,

(e) a safety tripper in said safety body pivotally connected adjacent said pin rod and extending from said `safety body when said rotatable pin is in said first position,

(f) pivotal connection means extending into said safety body and transverse to said firing pin rod for pivotally connecting said safety tripper to said safety body,

(g) shear pin means extending through said safety tripper and into said safety body,

(h) a safety block having first and second ends and operably connected at said first end to said rotatable pin and engaging said safety tripper at said second end when said rotatable pin is in said first position.

(i) a safety spring mounted with safety body parallel to said firing pin body and connected to said safety block at said first end and attached to said safety body below said rotatable pin, and

(j) said safety tripper disengaging said second end of said safety block and pivoting into said body by shearing said shear pin means of said safety tripper in said collar of said pipe when said tool is moved upwardly in said pipe whereby said spring pulls said first end of said block in a downward direction, thereby rotating said rotatable pin to a second position which reduces coaction between said rotatable pin and said firing pin rod to allow said ring pin rod to move longitudinally for contact with said firing pin. 7. In a well tool having an explosive charge and a firing pin adapted to detonate same, the improvement residing in a safety means for preventing premature detonation of said explosive charge, comprising:

(a) a housing, Y. (b)Y arrodV insaidV housingmand adapted to be actuated by the firing pin; said rod having an arcuate recess:

for longitudinal movement relative to said housing,

(c) a latch pin mounted on said housing transversely and substantially perpendicular to said rod and Coacting with said recess of said rod to prevent movement of said rod relative to said housing,

(d) a safety block operably connected to said latch pin,

(e) a `safety tripper engaging said safety block, and

(f) means for releasing said tripper from engagement with said safety block including a safety spring `mounted with said housing engaging said safety block and attached to said housing to move said safety block relative to said safety tripper to release said safety pin from holding engagement with said rod, thereby moving said rod longitudinally relative to said housing.

8. In a well tool having an explosive charge and a ring pin to detonate same for positioning a flow control device in pipe having a collar, the improvement residing in safety means comprising:

(a) a housing having a longitudinal bore therein,

(b) a cylindrical rod adapted to engage said firing pin to actuate same and having a curved arcuate recess positioned longitudinally in said bore for longitudinal movement relative to said housing,

(c) a rotatable pin having a curved arcuate recess on one side mounted transversely and substantially perpendicular on said housing and coacting with said curved arcuate recess on said rod on the opposite side from said curved arcuate recess on said side of said rotatable pin,

(d) a rotatable safety block operably connected at one end to said rotatable pin,

(e) a spring mounted with said housing and attached to said safety block for urging rotation of said safety block,

(f) a releasable tripper mounted on said housing and extending from said housing and engaging the other end of said rotatable safety block when the curved arcuate recess on said rod coacts with said rotatable pin on the opposite side from the curved arcuate recess on said pin, and

(g) means -mounted on said tripper for preventing re- 'leasement of said tripper until said tool is moved upwardly .to engage said tripper with said collar of said pipe whereby said tripper is released to permit said spring to urge rotation of said block and said rotatable pin until the curved arcuate recess on said pin rotates to arcuately t said cylindrical surface of `said firing pin rod to permit movement of said rod longitudinally relative to said housing.

9. In a tool having a firing pin for firing an explosive charge in pipe having a collar, the improvement residing in safety means for preventing accidental firing of said charge comprising:

(a) a housing having a `longitudinal bore,

(b) a cylindrical rotatable pin having a curved recess mounted transversely and substantially perpendicular with said housing,

(c) a cylindrical rod having a curved arcuate recess positioned longitudinally in said bore of said housing and coacting with said cylindrical surface of Said rotatable pin at said curved arcuate recess of said rod to prevent longitudinal movement of said rod relative to said ring pin,

(d) means operably connected to said rotatable pin for urging rotation of said pin to move said curved recess of said pin into alignment with the external surface of said rod,

(e) a safety tripper mounted with and extending from said housing and engaging said means operably connected to said pin to prevent said means from urging rotation of said pin, and

(f) a shear pin mounted on said tri-pper to prevent said tripper from disengaging said means until said pin is sheared moving said tool upward to engage said tripper in said collar of said pipe whereby said means urges rotation of said rotatable pin until the curved recess on said pin rotates to engage the similarly curved cylindrical surface of said rod to thereby permit said rod to move longitudinally for contact with said firing pin.

10. In a well tool having an explosive charge and a firing pin for detonating same, the improvement comprising:

(a) a housing having a longitudinal bore therein,

(b) a cylindrical rod for actuating said ring pin to detonate said explosive charge and having a curved recess positioned in said bore for longitudinal movement relative to said housing,

(c) rotatable means mounted with said housing coacting with said curved recess of said rod to prevent longitudinal movement of said rod relative to said housing,

References Cited UNITED STATES PATENTS 2,251,125 7/1941 Gardner 166-237 X 2,373,006 4/1945 Baker 16S- 55.3 X 2,482,913 9/1949 .TObe 16S- 55.3 X 2,559,687 7/1951 Thomas 166--551 X 2,638,981 5/1953 Bannon et a1 175-4.54 X 2,885,231 5/1959 Smith 287-119 X 2,655,993 10/1953 Spencer 175-4.56 X 3,105,549 10/1963 Raulins 166-63 X 3,176,770 4/1965 Ehlert 166-553 X 3,199,287 8/1965 Kinley 166-63 X CHARLES E. OCONNELL, Primary Examiner. I. A. CALVERT, Assistant Examiner. 

